Internal-combustion-radiator-unit heating system and method of operating same



F. W. SHUELL ET AL INTERNAL COMBUSTION RADIATOR UNIT HEATING SYSTEM ANDMETHOD OF OPERATING SAME Filed Sept. 14, 1925 s Sheets-Shut 1 In m \N lJ J[ m i 7* 7* I H 1 l lance/T4 60? m, 9km A441! 10m July 27,1926.

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UNITED STATES 1,594,074 PATENT OFFICE- ERAN K W. SHUELL AND ELMER E.LEDBETTER, OF DETROIT, MICHIGAN, ASSIGNORS TO EVERHOT HEATER COMPANY, OFDETROIT, MICHIGALL. A CORPORATION OF MICHIGAN.

INTERNAL-COMBUSTIONRADIATOR-UNIT HEATING SYSTEM AND METHOD OF OPERATINGSAME.

Application filed September 14, 1925. Serial No. 56,330.

The invention relates to heating systems of that type employing aplurality of combined convection and radiation units individuallyoperated by internal combustion.

Heretofore systems have been tried in which the individual units havebeen heated by gaseous fuel, the products of combustion being drawn awaythrough an exhaust conduit. Such systems have, however, provenunsatisfactory and of short life due to various causes among which are,first, lack of efiiciency in extracting the heat from the combustiongases, and second, excessive cor-' rosion caused by the products ofcombustion; third, the existence of hot spots in the outer surface andconsequent danger of fire.

The burning of any fuel having a hydrogen -content results in thegeneration of water vapor which, when condensed and commingled withother products of combustion such as sulphur dioxide, will produce ahighly corrosive agent. This, collecting on the walls of the radiator orthe conduit through which the combustion gases are exhausted, will soondestroy the same. On the other hand, if condensation is avoided by theexhaustion of the gaseous products while still hot, this greatly reducesthe efiiciency and increases the cost of operation beyond practicallimits.

With our improved construction and method of operation, we have overcomethe difliculties above referred to, extracting most of the heat from theproducts of combustion, while avoiding any condensation of water vaporwhich would cause corrosion.

The broader features of our invention are applicable to systems usingvarious kinds of fuel but we shall specifically describe a system usinggaseous fuel.

In the drawings;

Figure 1 is a diagram illustrating the system of our improvedconstruction.

Figure 2 is a vertical longitudinal sec tion taken on the line,22 ofFigure 3.

Figure 3 is a cross section on the line 33 of Figure 2.

Figures 4, 5, and 6 are horizontal sections respectively on lines 44,5-5 and 6-6 of Figure 2.

Figure 7 isa section on the line 77 of.

As has been stated. one of the chief sources of trouble with such asystem is condensation of the products of combustion and consequentcorrosion of the apparatus. The effort is usually made to secure highefliciency by cooling down the products of combustion so as to extractmost of the heat therefrom. Therefore the temperature is dropped belowthe dew point where condensation occurs and if this is not done, theapparatus is inefficient. 'We have discovered that by limiting thequantity of air originally supplied to the combustion chamber to onlythat practically necessary for supporting combustion plus a certainproportion of air for preventing condensation in the unit itself and bydiluting the products of combustion with more air after most of with anexhaust conduit C from which the products of combustion are dischargedby suitable means such as the exhaust fan D. Each unit A comprises anouter casing E within which is arranged a combustion chamber F. Thiscombustion chamber merges into a progressively contracting flue- Gpreferably leading upward and then downward within the housing E andconnecting with the exhaust conduit C. The

combustion chamber as well as the flues G are surrounded by airconvection passages" which are open at their lower ends and con-1 nectedat their upper ends with a top chamber H discharging preferablylaterally through a grid I. The upper wall of the located in one or moreof the walls of the chamber. As specifically shown, a series ofcalibrated ports F are arranged in the front wall F of the combustionchamber. while the bottom wall F and rear walls F are imperforate. Thecombined'area' of all the inlet ports is predetermined so as to restrictthe amount of air entering the combustion chamber to the desiredquantity for preventing condensation. The contracting flue G has at itsupper end a header 0 which is connected at its opposite ends bytransversely extending conduits Pand P with a similar header Qconnecting with a downwardly extending and contracting flue G. At thelower end of. this flue G is an enlarged conduit R which communicateswith a bottom chamber S to which the exhaust conduit C is connected.There is also arranged in this bottom chamber adjacent to the exhaustconduit-an auxiliary air inlet preferably a series of ports T, T etc.,and

' the effective area of these ports can be varied by means of anadjustable valve or damper U. V is a partition or shield which isarranged in front of the combustion chamber F and upwardly extendingflue G to intercept the radiant heat of these parts. It also divides theair flue between the combustion chamber and the outer wall of the casingand by reason of the cooler air which will circulate through the outerpassage, an abnormal rise in temperature of the outer wall is prevented.In operation, the burners in the various units A are all lighted. but byreason of the thermostatic control of the; valve N the quantity of gasconsumed is dependent upon the temperature of the room to be heated. Theheat generated by the consumption of the gas and communicated to thegaseous products of combustion is dissipated first through the walls ofthe flue G to the air in the surrounding chamber. As this surroundingchamber is open at both bottom and topan ascending current of heated airwill be formed which will be discharged through the grid I at the upperend of the unit. The tapering form of the flue G provides for conraction in volume due to loss of heat with ut diminishing the velocityof movement through the flue. After reaching the top of the flue G theproducts are conducted through the header 0 and lateral conduits P and Pto the header Q which merges into the downwardly extendscribed and thedilution of the gaseous prod- 1 ucts of combustion are such that whenreaching the bottom chamber S the products of combustion are still at atemperature slightly above the dew point so that the water vapor contentremains uncondensed. If, however, the products in this condition weredrawn outward through a cold exhaust conduit, condensation of the vaporwould inevitably result. The condensed water commingling with corrosiveproducts such as sulphur dioxide would soon rust out the conduits andrender the apparatus short lived and inoperative. Such result we avoidby commingling with the products of combustion entering the bottomchamber S a sufficient quantity of air to lower the dew point below anydrop in temperature which may occur before the products are finallyexpelled from the exhaust conduit. The amount of air required dependsupon conditions of humidity and temperature and we have thereforeprovided the adjustable damper U for proper regulation. This damperperforms the further function of regulating the pressure drop in thechamber S which in turn controls the amount of primary air which isdrawn into the combustion chamber. The highest efficiency is producedwhere this quantity of primary air is only sufficient to supportcombustion and to avoid condensation within the unit itself. This limitsthe volume and increases the temperature of the gases while in the unitwith the consequent increased heat dissipation from the unit.

A further important feature of our construction is the means forguarding against overheating of any portion of the external surface. Theunit is not intended as a stove but as a substitute for a steam or hotwater radiator and this is frequently located adjacent to draperies andother imflammable material, therefore the temperature should not at anytime exceed 250 degrees F. On the other hand the efliciency is increasedby keeping this temperature as near the upper limit as-possible so thatit becomes very important to avoid hot spots and to maintainasubstantially uniform temperature in the external casing of the unit.It is also important to avoid loss .ofradiant heat to the exhaust gasesand this is accomplished lift) by the arrangement of shields orpartitions V and V, the former being arranged between the hottestportion 01'' the combustion chamber and theouter wall of the cas-- mg,and the latter between the combustion chamber and the rear flue forexhaust gases. As a result, the radiant heat intercepted by the shieldsis dissipated by convection of the air passing through the unit with thedouble advantage of avoiding hotspots in the external casing or loss ofheat in the exhaust products.

To maintain a uniform temperature it is desirable to providethermostatic control which increases or diminishes the quantity of gassupplied to the unit. As illustrated.

W is a thermostatic unit of any suitable construction which controls avalve- VV' n the gas supply conduit adjacent to the vunit.

' X on the inner side thereof. Thus, the

, unit, such that the amount of air admitted to said unit is limitedsubstantially to that necessary for complete combustion plus the amountnecessary for preventing condensation within said unit.

2. The method of operating an internal combustion radiator unit havingfuel and air inlets and an exhaust conduit, said method consisting increating a suction within said exhaust conduit and admitting a variablequantity of auxiliary air into said exhaust conduit to control thesuctionefi'ective on said unit whereby an amount of air is drawn throughsaid air inlet sufficient for supporting combustion and preventingcondensation within the unit.

3. The method of operating an internal combustion radiator unit havingfuel and air inlets and an exhaust conduit for carrying away theproducts of combustion from said unit which consists in creating asuction within said exhaust conduit for withdrawing the ro'ducts ofcombustion from said unit an admitting a predetermined amount of air tocommingle with the roducts of combustion entering said ex aust conduitwhereby the rate of flow of said products'through the unit is such as todissipate the heat therefrom to lowen. the temperature to near thedewpoint-and the dew point of said mixture is lowered to less than shetemperature within the exhaust conuit.

4. The method of operating an internal combustion radiator unit havingfuel and air inlets and an exhaust conduit for carrying away theproducts of combustion which consists in admitting a predeterminedamount of air to both said unit and said exhaust conduit, the airadmitted to the unit being only sufficient to support combustion andpreventcondensation Withiirthe unit and the air admitted to the exhaustconduit being such as to lowervthe dew point of the diluted mixture toless than the temperature thereof in the exhaust conduit.

5. A heating apparatus comprising an internal combustion radiator unit,means for supplying fuel thereto, means for supplying primary airthereto, a casing surrounding said unit and open for the passage of airtherethrough to extract the heat from said unit to lower the temperatureof' the same to approximately the dew point, a suction conduit forwithdrawing the products of combustion from said unit and means forintroducing a variable quantity of air into said suction conduit forvarying the effective suction-on said unit and thereby regulating theamount of primary air admitted to that necessary for supportingcombustion plus an amount sufficient to prevent condensation within saidunit. 7 p

6. A heating apparatus comprising an internal combustion radiator unithaving calibrated air inlets and a fuel inlet, a casing surrounding saidunit and open for the passage of air therethrough to extract theheatfrom said unit, a conduit through which the products of combustionin said unit are withdrawn, means for placinga predetermined suction onsaid unit so proportioned to said air inlets as to permit theabstraction of the heat from the products of combustion to lower thetemperature of the same to approximately the dew point, and means forcommingling additional air with said products before exhausting the sameto lower the dew point thereof.

7. A heating apparatus comprising an internal-combustion radiator unit,means for supplying fuel to said unit, means for admitting a limitedsupply of air to support combustion and prevent condensation within thesaid unit, means for extracting the heat from the products of combustionto lower the temperature of the same to near the dew point, a conduitthrough which the products of combustion are withdrawn from said unitand means for'commingling additional air with the products of combustionwithdrawn through said conduit to lower the dew point thereof below thelowest tem-' perature in said exhaust conduit.

8. A heating apparatus comprising an internal combustion radiator unit,a casing surrounding said unit and open for the passage of airtherethrough, a suction conduit through which products of combustion inI said unit are withdrawn, means for prede termi'ning the velocity oftravel of sald products through said unit to abstract the heat therefromto lower the temperature thereof to approximately the dew point, andmeans for commingling additional air with said products beforeexhausting the same to lower the dew point thereof.

9. A heating apparatus comprising an in-' ternal combustion radiatorunit, an exhaust conduit connected with said unit, means for creating asuction in said exhaust conduit, means for regulating the flow of thegaseous products of combustion through said radiator unit to limit thequantity of air admitted to substantially the amount necessary forsupporting combustion and preventing condensation within the unit, meansto extract heat from said products to lower the temper-" ature thereofto approximately the dew point thereof, and means for commingling airwith said products before exhausting the same to lower the dew point ofthe mixture.

10. A heating apparatus comprising an internal combustion radiator unit,an exhaust conduit for the products of combustion connected to saidunit, means for producing a suction within said exhaust conduit andregulable means for admitting air to commingle with the products ofcombustion before'exhausting the. same to said conduit whereby thequantity of air for supporting combustion is limited, the speed of flowthrough the unit is retarded to lower the temperature to approximatelythe dew point and the dew point of the commingled air and products islowered to a point below the temperature within said exnaust conduit.

11. An internal combustion radiator unit comprising a combustionchamber, means for supplying fuel to said combustion chamber, means forsupplying air thereto, a casing surrounding said unit and open for thepassage of air therethrough to extract the heat from said unit, a fluewithin said casingthrough which the products of combustion in saidcombustion chamber are withdrawn, a suction conduit connected with saidflue and means for admitting a variable amount of air to commingle withthe products of combustion in advance of entrance to said suctionconduit.

12. An internal combustion radiator unit comprising a casing having airinlet and outlet openings respectively in the lower and upper portionsthereof, a combustion chamber within said casing and spaced from thewalls thereof, air and gas inlets for said combustion chamber, aprogressively contracting vertical flue within said casing spaced fromthe wallsthereof, an exhaust oonduit connected with said flue and meansfor admitting auxiliary air to commingle with the products of combustionpassing from said flue into said exhaust conduit.

13. An internal combustion radiator unit comprising a casing open forthe passage of air therethrough, a combustion chamber therein, means forsupplying fuel to said combustion chamber, a flue also within saidcasing through which the products of combustion are withdrawn from" saidcombustion chamber, and a shield within the air passage of said casingfor intercepting the radiant heat from a high temperature portion ofsaid combustion chamber.

14. An internal'combustion radiator unit comprising a casing open forthe passage of air therethrough, a combustion chamber therein, means forsupplying fuel to said combustion chamber, means for supplying air tosaid combustion chamber, a flue also within said casing through which.the prod nets of combustion are withdrawn from said combustion chamberand means for intercepting the radiant heat from said combustion chamberand flue to prevent overheating of said outer casing.

15. An internal combustion radiator unit comprising a casing open forthe passage of air therethrough, a combustion chamber therein, means forsupplying fuel to said combustion chamber. a flue also within saidcasing through which the products of combustion are withdrawn from saidcombustion chamber, and a shield within said air passage between thehigh temperature portion of said combustion chamber'and said outercasing for intercepting the radiant heat from the combustion chamberwhereby excessive heating of any portion of the outer casing is avoided.

16. An internal combustion radiator unit comprising a casing open forthe passage of air therethrough, a combustion chamber therein, means forsupplying fuel to said combustion chamber, a progressively contractingflue also within said casing and extending downward therein parallel .tosaid combustion chamber and shields within the air passage forintercepting the radiant heat from the hotter portions of saidcombustion admitting a variable amount of air to commingle with theproducts of combustionin advance of entrance to said suction conduit,and means for shielding the outer casing from radiant heat of saidcombustion chamber to avoid overheating of the casing.

18. A heating apparatus comprising an internal combustion radiator unit,an exhaust conduit connected thereto, means for placing a predeterminedsuction on said exhaust conduit, 2, burner within said unit having afuel supply connected thereto, and means for introducing into said unitindependently of said burner a predetermined amount of air more thansufficient to support complete combustion and limited to substantiallythat necessary for preventing condensation within the unit.

19. A heating apparatus comprising an internal combustion radiator unit,a burner within said unit having a fuel supply con nected thereto, meansfor placing a predetermined suction on said unit to exhaust the productsof combustion therefrom, said unit being provided with radiation surfacefor abstracting the heat from the products of combustion therebylowering the temperature thereof, and means for introducing into saidunit independently of said burner a predetermined amount of air morethan suflicient to support complete combustion and limited tosubstantially that necessary for. preventing condensation within theunit.

20. A heating apparatus comprising an internal combustion radiator unit,a burner within said unit having a fuel supply connected thereto, meansfor placing a predetermined suction on said unit to exhaust the productsof combustion therefrom and inlet means for introducing air into saidunit independently of said burner, said unit being provided withradiation surface for abstracting the heat from the products ofcombustion thereby lowering the temperature thereof, said air inletmeans and said suction means being so proportioned that the amount ofair drawn through said unit is more than sufficient to support completecombustion and is limited to substantially that amount'necessary forpreventing condensation within said unit.

In testimony whereof we afiix our signatures.

FRANK W. SHUELL. ELMER E. LEDBETTER.

